There are numerous areas where control based on temperature is desired. Many of such devices are manually controllable, such as wall vents, for example. However, manual operation takes a great deal of time and effort, and may be inaccessible, such as, for example, ridge vents that are located a substantial distance from the floor of the area to be controlled.
In addition, the devices to be controlled may be many, as for example, in areas such as greenhouses. Obviously, covers or ventilating units on greenhouses must be opened to avoid temperatures which prevail inside the closed space limited by the frame of the greenhouse from reaching an undue level when sun rays directly strike the glass cover, and similarly the covers must be closed when the temperature decreases below a predetermined value, based upon the setting of the sun or a change in ambient conditions.
There have been disclosed systems for thermostatically controlling such ventilating devices, but such have been based on electric input, or are expensively valved to afford satisfactory operation.
The present invention provides a simple device for the pneumatic control of such ventilating devices as wall ventilators, ventilating curtains, ridge vents, or any other device the control of which is based on temperature of an enclosed space.